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 Post subject: DIY manual air booster
PostPosted: Wed Nov 30, 2022 8:05 am 
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Joined: Tue Apr 27, 2021 7:53 am
Posts: 311
Location: East Of Hamilton
So, I purchased the cylinder from one of the 12v 4500 psi pumps from Aliexpress. My plan is to input pressurized air into through the breather hole and make a lever to pump the piston. The final stage piston appears to be about a 1/2". that gives me a force of 883 lbs required to compress at 4500 psi. plus the force of the pre-stage. I am going to make the lever handle so the ratio starts at 10:1 and adjustable by increments of 2 by moving the pivot pin or by adjustable handle length. I am thinking that in the shop it will be vise mounted and in the field it will be trailer hitch mounted. I plan to use a 12v compressor in filed to supply the air and use the trucks spare tire as my tank. I am still in the component acquisition phase.
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Have a great day all
Robert


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PostPosted: Wed Nov 30, 2022 4:18 pm 
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Location: Rocky Mtn Hse Alberta
Would love to see a sketch of assembly with piston dimensions

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PostPosted: Thu Dec 01, 2022 2:02 pm 
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Location: P.G. B.C.
I've seen booster pump systems used by Mr. Hollowpoint, for boosting a low pressure tank up to 4,500psi,
but do not understand the process or setup. The concept I get, the process, no.

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Daryl


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PostPosted: Thu Dec 01, 2022 2:11 pm 
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Location: Rocky Mtn Hse Alberta
How I think he is doing this makes me wonder how it would ever fill a gun?

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PostPosted: Thu Dec 01, 2022 7:12 pm 
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Joined: Sat Jul 11, 2020 5:36 pm
Posts: 382
Location: Chilliwack, BC
Voltar1 wrote:
How I think he is doing this makes me wonder how it would ever fill a gun?


Perhaps by means of a reciprocating drive?

There have been a number of projects online which used motor-driven crank and linkage arm.

Since a YH can be purchased for ~$300.00, I dropped the idea, but it's always interesting to see what others make.

Here's the first one I grabbed off YouTube. The same system might be applied to the compressor in question.

I have an old one in my parts bin. A friend overheated his and melted the piston seal. It was less expensive to replace the cylinder assembly.

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PostPosted: Thu Dec 01, 2022 8:04 pm 
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Location: Coalmont BC
Here is the principle, I was asked how to boost pressure without another air source.... Red and blue lines represent valves....

Image

The problem is that you have to vent some of the source air to atmosphere to reset each stroke, losing a lot of it.... In most commercial boosters, there is a much larger difference in piston areas, and the booster is driven by another air source of ~150 psi (eg. shop) air.... You can get that from a regulator from and HPA tank, but again, you are losing HPA with every stroke.... Here is a screw driven version....

Image

and here is one driven by hydraulics....

Image

This is the most common version, with the booster section driven by an air cylinder.... It compresses the HPA on the "pull" stroke....

Image

Here is the piston, mounted on the threaded shaft of the air cylinder (from Princess Auto).... 80mm bore and 200mm stroke, running on shop air....

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Inlet air from the HPA source tank was controlled through the valve in the male foster, and the manifold had a bleed valve installed beside the pressure gauge.... Unfortunatey, I could not cure the O-ring leaks.... The most successful design I saw was by Gippeto, who used a brake booster from a Semi as the driving mechanism....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
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PostPosted: Thu Dec 01, 2022 9:05 pm 
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Joined: Tue Apr 27, 2021 7:53 am
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Location: East Of Hamilton
I did start this morning writing a long essay about boosters but Bob beat me to it.

In my version the force to compress the cylinder will be man power. If I was drawing in 1 atmosphere which is about 14.7 psi then I would referred to it as a pump. Seeing as I will be inducing compressed air into the cylinder is why I am calling it a booster. My micro shop compressor has a cut off of 225 psi. I will starting off with the induced air pressure low say around 15 lbs, I will monitor the heat generation as I increase the pressure. The maximum force need to get to 4500 psi will only be in the bottom of the stoke same as all hand pumps. Last winter when I went south I took my YH compressor with me, I hope this year to leave it at home this year.


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PostPosted: Thu Dec 01, 2022 11:32 pm 
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Location: Coalmont BC
I assume it is a 2-stage compressor, primary in one direction and secondary in the other?.... hence the copper tube connecting the two ends?.... What is the total stroke?.... Your handle travel will be that times your leverage ratio, of course.... If you use too high a feed pressure, you might need more force for the 1st stage than the second.... The "best pressure" for your inlet feed air will be determined by the ratios of the piston diameters, and the ergonomics of "pulling" on the lever as compared to pushing on it.... The number of strokes required will be determined by the swept volume of the 2nd stage and the internal volume of the bottle you are filling, and of course the fill pressure and pump losses....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!


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PostPosted: Fri Dec 02, 2022 1:17 am 
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Location: Rocky Mtn Hse Alberta
McRobert, what is the config of the shown cylinder? How was it operated on 12 volts?

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PostPosted: Fri Dec 02, 2022 6:24 am 
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Location: East Of Hamilton
Bob there is a second cylinder inside that can not seen which is the inside of the visible piston rod. Stage 1 is from outer cylinder to the inner cylinder compression stroke, Stage 2 is from the piston rod to the outer cylinder retraction stroke and stage 3 is the inner cylinder. I do not want to take it apart to measure dia. in order calc end area of each piston to derive at a theoretical force required for each pressure. If I do disassemble the pump then I will provide a spreadsheat showing the amount of ambient air that is used at each pressure along with the force needed for each stage and number of strokes used to fill said volumes. By having my first handle being adjustable in length and fulcrum point I will able arrive at the Ideal handle configuration, before I make it out of aluminum. It is possible that my handle may be slotted at the fulcrum to allow one ratio at low pressure and a different ratio at higher pressure

Have a great all
Robert


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PostPosted: Fri Dec 02, 2022 5:37 pm 
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Location: Rocky Mtn Hse Alberta
I wonder if you considered strokes to build a useful air volume?
Keep at it

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PostPosted: Sat Dec 03, 2022 11:12 pm 
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Location: Canada
Have been thinking of compressors lately as well, and eyed those cylinders. More likely I will do something different....I tend to march to my own drum lol.

Will be interesting to follow your build though.

For the curious...in its original configuration, the pump uses a large diameter dc motor (presumably brushless but not sure) running a generous gear reduction feeding into a scotch yoke to generate the stroke.

Al


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PostPosted: Sun Dec 04, 2022 3:08 pm 
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Location: Rocky Mtn Hse Alberta
Thank you Al, that is what I was wondering about so likely about 100 strokes per minute?

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PostPosted: Sun Dec 04, 2022 3:20 pm 
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Rough guestimate at roughly double that...seems like about 3 cycles per second.

https://youtu.be/4vgfS55ZuAM?t=189

Al


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PostPosted: Sun Dec 04, 2022 10:35 pm 
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Be quite a challenge to stroke it manual tee hee

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